1. Field of the Invention
The invention pertains to the field of sheet-fed document scanners. In particular, the present invention relates to an anti-skew auto-start system for high-speed scanners.
2. Description of the Related Art
Existing sheet-fed document scanners have the tendency to skew documents and the resulting image either must be de-skewed by post processing or the document may have to be re-scanned. De-skewing by post processing, however, degrades image quality. Furthermore, when skew is significant, the paper hits a side of the scanner, hence crushing or tearing it. The skew problem is significantly aggravated with fast scanners having a scanning speed of over 200 mm per second. Any misalignment in the introduction of the paper will be amplified when the feed roller seizes the paper.
Skew problems reduce quality and productivity significantly. Only sophisticated, fast and expensive sheet-fed scanners are equipped with belt or roller mechanisms that ensure paper skew is reduced or eliminated. Consumer type or personal type sheet-fed scanners, however, do not have any mechanism to eliminate paper feed skew.